What is the most comfortable way to play?

My buttons are assigned like this:

A - Triangle
S - Square
Semi colon button - Cross
Quote button - Circle

And as for the L and R arrows I use the Shift buttons respectively.

Do you think this is a comfortable way of playing?

It's up to you if it's enough comfortable way. But since all buttons in right order (Lslide, triangle, square, cross, circle, Rslide), i say "yes".

I agreed with KuMiKuPa
If you're get used with the right order, you just need to find the position that makes your fingers comfort.

My keyboard settings:
← △ □ × ○ →
LeftShift z x DownArrow RightArrow RightShift

I use the LeftShift and Numpad0 with a reason, because it easily pressed since it have a long shape.